Presently, various types of engines are used for generating rotary power and most of them are running on fossil fuels, like gasoline, diesel, natural gas, biodiesel, etc. Since the conception of the internal combustion engine engineers have attempted to reduce the size of fuel particles as much as possible when injecting liquid fuel into a cylinder to obtain better burning conditions. For this purpose we have nowadays various advanced fuel injection systems, like common rail and other types of fuel injection systems injections for injecting fuel into the engine cylinders. Even nowadays engineers are still attempting to reduce the size of the liquid fuel droplets/particles as much as possible with high pressure.
There are many technical problems that need to be solved if really good conditions for burning are to be obtained. High pressure pumps, piping, injectors and many parts connected in the system are very complicated and with more possible problems and faults if extremely high pressure is used and maintenance gets more complicated.
Basically, all kinds of hydrocarbon fuel need to be blended with oxygen from air, e.g. in a cylinder, to get a condition of burning or oxidizing.
Oxidation of fuel in the cylinder is directly connected to the dimensions or better to say to different state of matter in the fuel and in liquid form the hydrocarbon fuel is completely different than in gas form. Much better burning and oxidation conditions can be obtained if gaseous fuel is used, and nowadays there already have many applications with gaseous fuel systems on cars, trucks and other engines. These engines are usually diesel or gasoline engines. In both cases a separate system for gaseous fuel injection and for liquid state fuel injection needs to be installed on the engine, i.e. two separate injection systems are required. Usually, gaseous fuel comes into the engine cylinder though the air intake and often there are operation problems with other parts of fuel system, like injectors, high pressure pumps, etc. Sometimes the gaseous fuels have very poor lubrication characteristics compared to liquid fuel and therefore after some time of use parts of the fuel injection system can be damaged.
At the same time gas installation systems on engines are complicated, expensive and we still need to fill liquid fuel into a separate tank placed somewhere in the car or other vehicle thereby wasting space that can be used for other purposes. The gas tank needs to be filled with gaseous fuel, which requires an infrastructure like gas stations distributed over a region. Filling the gaseous fuel into the tank can be even dangerous and hazardous matters are to be taken care of.
Gas as a fuel is more dangerous than liquid fuel because it can be better mixed with oxygen in the air and even from an explosive mixture explosive in a given concentration.
There is though one more reason for using gaseous fuel for combustion. Nowadays, we use many different kinds of gases like natural gas extracted from the gas fields and gas produced from fuel in refinery as fuel. In order to produce gas from fossil fuel energy needs to be added and this can be as much as 35% of energy that can be produced by the gaseous fuel. So the overall efficiency when producing gas from liquid fossil fuels is not good.
Gaseous fuels have some benefits as well, like less pollution and for example better burning conditions and fewer pollutants like NOx and CO.
This is the main reason why it would be of great advantage to be able to use partly gasified liquid fuel.